EEG Dynamics: BBS Call for Commentators

[Stevan Harnad]

    Below is the abstract of a forthcoming target article on:

    BRAIN DYNAMICS, EEG & NEURAL NETS by JJ Wright & DTJ Liley

This article has been accepted for publication in Behavioral and Brain
Sciences (BBS), an international, interdisciplinary journal providing
Open Peer Commentary on important and controversial current research in
the biobehavioral and cognitive sciences.

Commentators must be current BBS Associates or nominated by a current
BBS Associate. To be considered as a commentator for this article, to
suggest other appropriate commentators, or for information about how to
become a BBS Associate, please send email to:

bbs at ecs.soton.ac.uk or write to:

    Behavioral and Brain Sciences
    Department of Psychology
    University of Southampton
    Highfield, Southampton
    SO17 1BJ UNITED KINGDOM
    http://cogsci.ecs.soton.ac.uk/~harnad/bbs.html
    gopher://gopher.princeton.edu:70/11/.libraries/.pujournals
    ftp://ftp.princeton.edu/pub/harnad/BBS
    
To help us put together a balanced list of commentators, please give
some indication of the aspects of the topic on which you would bring
your areas of expertise to bear if you were selected as a commentator.
An electronic draft of the full text is available for inspection by
anonymous ftp (or gopher or world-wide-web) according to the
instructions that follow after the abstract.
____________________________________________________________________

        DYNAMICS OF THE BRAIN AT GLOBAL AND MICROSCOPIC SCALES:
        NEURAL NETWORKS AND THE EEG.

                J.J. Wright and D.T.J. Liley

                Mental Health Research Institute Parkville
                Victoria 3052, Australia
                jjw at cortex.mhri.edu.au

                Swinburne Center for Applied Neuroscience
                Hawthorne, Victoria 3122
                Melbourne, Australia

    KEYWORDS: chaos, EEG simulation, electrocorticogram, neocortex,
    network symmetry, neurodynamics.

    ABSTRACT: There is some complementarity of models for the
    origin of the electroencephalogram (EEG), and neural network
    models for information storage in brain-like systems.
    From the EEG models of Freeman, Nunez, and the author's group,
    we argue that the wave-like processes revealed in the EEG
    exhibit linear and near-equilibrium dynamics at macroscopic
    scale, despite extremely nonlinear, probably chaotic, dynamics
    at microscopic scale. Simulations of  cortical neuronal
    interactions at global and microscopic scales are then
    presented. The simulations depend on anatomical and
    physiological estimates of synaptic densities, coupling
    symmetries, synaptic gain, dendritic time constants and axonal
    delays. It is shown that the frequency content, wave
    velocities, frequency/wavenumber spectra and response to
    cortical activation of the electrocorticogram (ECoG) can be
    reproduced by  a "lumped" simulation treating small cortical
    areas as single functional units. The corresponding cellular
    neural network simulation has properties which include those of
    attractor neural networks proposed by Amit, and Paresi.
    Within the simulations at both scales, sharp transitions occur
    between low and high cell firing rates. These transitions may
    form a basis for neural interactions across scale.
    To maintain overall cortical dynamics in the normal low
    firing-rate range, interactions between the cortex and
    subcortical systems are required to prevent runaway global
    excitation. Thus the interaction of cortex and subcortex via
    cortico-striatal and related pathways, may partly regulate
    global dynamics by a principle analogous to adiabatic control
    of artificial neural networks

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To help you decide whether you would be an appropriate commentator for
this article, an electronic draft is retrievable by anonymous ftp from
ftp.princeton.edu according to the instructions below (the filename is
bbs.wright). Please do not prepare a commentary on this draft.
Just let us know, after having inspected it, what relevant expertise
you feel you would bring to bear on what aspect of the article.
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    http://www.princeton.edu/~harnad/bbs.html
    http://cogsci.ecs.soton.ac.uk/~harnad/bbs.html
    gopher://gopher.princeton.edu:70/11/.libraries/.pujournals
    ftp://ftp.princeton.edu/pub/harnad/BBS/bbs.wright
    ftp://cogsci.ecs.soton.ac.uk/pub/harnad/BBS/bbs.wright

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cd /pub/harnad/BBS
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